Driving in steel pipes, for example protective or line pipes, with the aid of a rammer whose impact point or head engages, directly or by means of a rammer attachment, in the rear end of a steel pipe, generally requires a starting hole or a shaft in which the rammer and steel pipe are prepared for pushing forward into the ground. The hole must have a minimum length given by the sum of the length of the pipe to be rammed in and the length of the rammer (cf. German Offenlegungsschrift 33 26 246).
To reduce the dimensions of the starting hole the lengths of the pipe to be rammed in can for example be shortened: for example instead of 6 m the length can be only 4 m. This however would result in correspondingly more frequent and time-consuming re-fitting of the rammer and connection of the shorter sections of pipe to the finished length. It is therefore sought to make the sections of a steel pipe to be rammed in as long as possible, and a correspondingly longer starting hole is accepted.
The length of the rammer is determined by the thrust needed to push forward the steel pipe, which is applied by the mass of the percussion piston, which may weigh several tons, that is reciprocated in the housing by means of compressed air supplied through a compressed air line. In known rammers externally threaded cylindrical attachments on the impact head and the cover closing the housing at the end opposite the head are screwed into the housing, which has corresponding internal threads. The length over which they are screwed in is thus lost from the stroke of the percussion piston, which means that with a given diameter the length of the housing must be increased for it to be able to receive the length of the percussion piston determined by the mass for the required thrust.